Recently, there is a demand for a larger transmission capacity along with the increase in the amount of communication over the Internet and the like. In conventional transmission systems via copper cables, it is becoming difficult to achieve such a large transmission capacity. Therefore, optical communication that can achieve a larger transmission capacity has been proposed.
A so-called physical contact (PC) system of abutting optical fibers to each other in a connector is adopted for optical communication cables generally used at present. In the PC system, however, highly-accurate adjustment is required for aligning the both optical fibers. In addition, in the abutment of the optical fibers, the both optical fibers need cleaning every time connection is made in order to prevent waste or the like from adhering to the tips of the optical fibers to damage the optical fibers. Further, in the PC system, in order to suppress a coupling failure in a gap between the leading ends of the optical fibers, injection of a refractive index adjuster into the gap is indispensable. From these results, it is difficult for general users to insert and remove optical fibers by the PC system.
As a method for solving these problems, a collimating optical coupling system has been proposed. In the collimating optical coupling system, each lens is mounted with the optical axis aligned at the tip of each optical fiber, and an optical signal is turned into parallel light to transfer the optical signal between opposed lenses. By using such a collimating optical coupling system, the accuracy in aligning connectors of optical fibers to each other is relaxed. Further, in the collimating optical coupling system, since optical fibers are optically coupled to each other in a contactless state, an adverse effect on transmission quality caused by waste or the like intruded between the optical fibers is also suppressed, and the need for frequent and careful cleaning is also eliminated.
In the meanwhile, parallel light used in the collimating optical coupling system is theoretically less likely to attenuate even at a distance from an output section, and, depending on the intensity, it is difficult to satisfy standards concerning laser light, such as IEC 60825-1 and IEC 60825-2. Therefore, at present, a shutter for shielding parallel light during disconnection is provided for an optical communication connector.
In addition, Patent Literature 1 proposes an optical connector having an object to prevent laser hazard due to collimated light (parallel light). Specifically, an optical connector for performing collimating optical coupling is disclosed in which opposed two projection-recess structures are provided for an optical fiber fixing section and a collimating lens. In this optical connector, during disconnection of the optical connector, the collimating lens separates from the optical fiber fixing section, and the projection-recess structures scatter light from optical fibers. On the other hand, in this optical connector, during connection of the optical connector, the collimating lens is pressed, so that the collimating lens comes into contact with the optical fiber fixing section with the two projection-recess structures interposed therebetween to eject parallel light.